Engine manufactures in developed countries are continuously challenged to improve the fuel economy and performance of vehicles in the market place. The original equipment manufacturers for vehicles are being pressured to meet and exceed the Environmental Protection Agency's Corporate Average Fuel Economy (CAFE) requirements as well to reduce the vehicles fuel consumption, which in turn would reduce the dependency on imported oil. CAFE is the sales weighted average fuel economy, expressed in miles per gallon (mpg), of a manufacturer's fleet of passenger cars or light trucks with a gross vehicle weight rating (GVWR) of 8,500 lbs. or less, manufactured for sale in the United States, for any given model year. Fuel economy is defined as the average mileage traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed as measured in accordance with the testing and evaluation protocol set forth by the Environmental Protection Agency (EPA). Further it is important to ensure that any compounds included in such fuel or lubricants used in vehicles are compatible with the fuels and base oils in order for the fuel and lubricants to function with vehicles without negatively impacting its operability or performance.
For example, modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear. For years antiwear additives for high-performance oils such as zinc dialkyldithiophosphate (ZDDP) has been used that work by forming a protective polyphosphate film on engine parts that reduces wear. This film, referred to as a tribofilm or antiwear film (such as polyphosphate, zinc phosphate, zinc sulfide and iron sulfide), is worn away as engine is operated.